The present invention relates to improving the gloss in products made from rubber reinforced polymer resin blends, as for example, high impact polystyrene. In order to make rigid polymer materials such as polystyrene tougher, one incorporates thermoplastic elastomers into the resin blend. Larger elastomer particles tend to make the blends tougher, but detract from the glossy finish thereof. If the elastomer particles are smaller, the blends may have better gloss, but are not as tough.
Also, continuing addition of typically used thermoplastic elastomers reduces the melt flow rate of the resin blend and makes processing more difficult. As a result, rubber content is typically kept low to enhance processability and gloss, even though toughness might be further enhanced by additional elastomer content. A typical percentage of thermoplastic elastomer incorporated in impact polystyrene is less than about 10%.